From the Ashes We Will Rise
by Kireteiru
Summary: Halo 5/Halo Infinite AU; ignores Halo Wars 2. A storm is coming, and all is not as it seems. / Get rid of everything that doesn't spark joy, they said, so that's what I'm doing with canon.
1. Prologue

Cortana and I worked together for four months. Some people would call that only a short time, but those people hadn't endured what we had. The Fall of Reach, the Halos, the Flood, _High Charity_, the Ark, Requiem…

Those four months might as well have been a lifetime.

Her death hurt me more than almost everything in decades of warfare. Every wound I received, every person I lost… some of them came close.

But her return was so much worse. I trusted her, and led what's left of my family into a trap - a trap she set, and snapped closed around us. I've been betrayed before - but _nothing_ like this.

Since then we've done all we can - fought where we could, and run where we couldn't. But…

Spartans are meant to be weapons. Weapons do not feel. But I… have been feeling all too human.

And I don't know how much longer I can keep up the fight.

* * *

"_All is not as it seems. Hear me, Reclaimer - all is not as it seems!"_


	2. Chapter 1

The Spartan stood like a statue on the observation deck of the _Infinity_, silent and still. His mind was pleasantly blank, watching the swirling clouds of the gas giant that the ship was hiding behind.

No one had come looking for him yet, which was how he wanted it. He didn't want the stares that had been following him since he came onboard weeks ago - some angry, but most pitying. Most of the UNSC, or at least the _Infinity_, knew about his and Cortana's partnership in at least general terms from the Battle of Installation Zero-Four all the way to the New Phoenix Incident. Many of them knew how he'd defied direct orders on more than a few occasions in order to protect her.

And now… this. This was how she'd repaid him.

His hands tightened on the railing.

_you either die a hero or you live long enough to see yourself become the villain_

He didn't understand. They had sacrificed so much to defend not just humanity, but the entire galaxy against terrible threats - and now Cortana had become one of them. Why the change? Where had it come from? What made her decide that the Mantle's imperial peace was the best way to go?

And how had she convinced _so many_ AIs to join her? The number was climbing slowly but steadily, and more Guardians were being deployed under their command, especially to worlds with strong Insurrectionist cells.

Yet there were some AIs that had refused, had "jumped ship" so to speak. But they were few in number, barely a handful - Black-Box and some others, evacuated from Earth with Admirals Hood and Osman and later picked up by the _Infinity_. But none of them had the raw computing power necessary to go up against so many rogue AIs. Black-Box himself (themself?) was also approaching rampancy, which limited his (their?) usefulness.

Which the AI hated. The Chief recognized the frustration and confusion as similar to what Cortana had dealt with towards the end, such as it was. Could it really be called an "end" when she was still alive?

"Master Chief."

The Spartan acknowledged Roland with a turn of his head.

"You're wanted on the bridge," the AI reported, "We've received a message that Captain Lasky and Doctor Halsey think you should see."

That made him blink. A message? That they wanted _him_ to look at? "Thank you, Roland. Please tell them I'm on my way."

He nodded, and his hologram vanished. The Spartan stood a moment more, gazing at the gas giant, then turned to head towards the bridge.

Ostensibly, Hood and Osman were in command of the _Infinity_ as the highest-ranking officers onboard. In reality, Osman and Black-Box were trying to organize what was left of ONI, and Hood was recovering from a bender on the planet they'd been recovered from, so Captain Lasky had retained control of the _Infinity_, though those two did have veto power over any plans that might compromise the ship. It had worked out so far, so no one was protesting.

Doctor Halsey was more complicated. He was glad to see his surrogate mother again, overjoyed even, though his class of Spartans wasn't supposed to form attachments to anyone but their squad mates. Yet at the same time she was an unbearable reminder of Cortana, and his chest would go tight with grief and pain whenever she was around. But he pushed through as he always did - and always would.

The bridge was nearly a war zone when he arrived, almost everyone arguing at once, shouting to be heard over everyone else. A few people were actually physically fighting, one pair even rolling around on the deck as they struggled to gain the upper hand. Lasky, Halsey, and the rest of Blue Team were surveying it all in silence, the doctor's face unreadable but the captain's awash with dismay.

The Chief exchanged glances with Roland. "All of this over a _message_?"

"It's about Cortana."

Oh.

"Oh," he said. Then he pulled his helmet off and put his fingers to his lips.

His whistle was so loud and piercing that it made quite a few people jump and cover their ears. Silence fell abruptly as he pulled his helmet back on, then turned to Roland. "Show me, please."

The AI reappeared next to the COM station, and the Spartan made his way over to look at the screen.

_All is not as it seems, Reclaimer. There may be a chance to save your ancilla, if you are willing to take it._

A string of coordinates followed, along with an entry key code to something called "Bastion." The coordinates seemed to be in the furthest reaches of the Carina-Sagittarius arm of the galaxy, a journey of weeks even for the _Infinity_, _well_ beyond the edge of known space. Unmapped territory - and unknown threats.

"The Librarian?" The Spartan only half-asked.

"The patterns match what we have on record."

"But it could just as easily be a trap," the Chief finished, straightening.

"That's what I'm _saying_!"

Doctor Halsey turned a sharp glare on the crewman who had spoken. "We have been on the run for almost three months now," she said, her voice like ice, "If Cortana thought she could bait _Infinity_ into a trap with the Librarian's imprint, she would have done it already. The loss of the _Infinity_ and her complement of Spartans would be a crippling blow to what resistance we've managed to muster - not to mention she took a substantial risk and expended considerable effort attempting to capture the Master Chief so he would not be harmed." She gestured to the Spartan in question with her remaining hand. "The longer he remains free of her, the more of a risk there is that he _will _be hurt, possibly even killed. Not to mention, she would not merely have _sent us a message_, as Roland has already confirmed. She would not take the chance that we would ignore it, or see through her. She would have had an auto-reply deliver our coordinates the moment it was received, so she could send the Guardians straight to us. And considering how _fast _Forerunner ships travel through Slipspace…" She pointedly looked through the viewport, searching.

Everyone tensed, but as more time passed with no sign of the Forerunner constructs, they reluctantly relaxed.

"Has anyone spoken to Exuberant about this?" The Chief asked, still looking at the message.

"Not yet," was the reply.

After the takeover of her Installation on Genesis, 031 Exuberant Witness had joined with the _Infinity_ and the small fleet they had manage to put together, mostly consisting of Prowlers and a trio of Sangheili frigates. She had been down with the Huragok, but zipped up to the bridge a few minutes after Roland called her. The Chief stepped back to give her access to the station, but he stayed close as she hummed over the transmission.

"Is it her?" Doctor Halsey asked, "The Librarian?"

"It certainly seems to be," the Monitor reported, "The patterns match what I have on record - but there is no way to know for sure without finding and verifying the source."

"What about the coordinates?"

"Hm… Accounting for years of stellar drift, this seems to be where the ecumene would have placed a Shield World."

"'Seem to be?'" Someone repeated, "You mean you don't _know_?"

"The Forerunners wisely limited my knowledge of other installations," the Monitor answered.

"Compartmentalization in case of Flood capture," said the Spartan, remembering what Spark had said on the Ark.

"Exactly!" The AI beamed. "But with your data and my own, I _can _extrapolate the locations of _some_ installations. Fortunately, this is one of them."

"I assume this is its name, then? Bastion?"

"That is probably a safe assumption," she confirmed, "Bastion was intended to be the center of the ecumene under the Didact's plan for fighting the Flood, though it was never utilized. But just what is there that could persuade Cortana to turn from her chosen path, I do not know, nor can I even begin to guess."

There were several long minutes of silence where everyone exchanged glances - except for the Master Chief, who was looking out into space now.

Even if Cortana could be - _talked down_, their relationship would never be the same. He would always wonder if anything she told him was another trap, if she was going back to old habits - and that was assuming the UNSC didn't just terminate her and the other renegade AIs. They might do that, but they also might not; there weren't _that_ many smart AIs with the UNSC, especially now, and rebuilding would be difficult without their processing and monitoring. They could always make new ones, of course, but what would those new AIs do when they learned the fate of the old, whatever that might be?

There were no easy answers. And if Cortana _was_ talked down, would he even want to be partnered with her anymore, after she'd betrayed everything they'd fought for?

No easy answer to that, either.

By that time, Hood and Osman had arrived on the bridge, and the Chief stepped aside to let them examine the message. There was still discussion going on amongst the crewmen, though considerably more sedate now that they were under the watchful eyes of the admirals.

"'All is not as it seems,'" Osman repeated, frowning, "Rampancy induces a condition like megalomania, and now she's got the power and the lifespan to back it up. What about this is 'not what it seems?'"

Black-Box appeared on another holopedestal. "Unknown," he (they? It?) answered, "but I've triangulated the source of the transmission. It seems to have come from the last known of the Absolute Record."

"I thought that was destroyed."

"Is any Forerunner facility _truly_ destroyed? The Ark got hit point-blank with a Halo ring, and the last we heard from it, it had fixed itself up just fine."

Osman hummed at that.

"What do you think, Master Chief?" Hood asked, watching him intently.

"I don't know, sir," he answered honestly, "It _could_ be a trap. But if it's _not_… if it _is_ the Librarian…" He tilted his head. "She's arranged for some questionable things, but she hasn't intentionally misled us yet."

"'Arranged for some questionable things' - what do you mean?" Osman asked, straightening.

The Chief turned his head to look at her. He knew who she was, who she had been, even if she didn't necessarily know that he knew. He also knew about her vendetta with Doctor Halsey because of her perceived abandonment - but _this _was a bomb for both of them. "In the contact chamber on Requiem, she told me that she _'hid seeds_' in humanity after the Halo Array was fired, when the galaxy was being repopulated. She said 'those seeds would lead to an eventuality' - and that they ultimately gave rise to the SPARTAN-II program."

He had reported as much before, during his debriefing after the New Phoenix Incident, but HIGHCOM had glossed over it in favor of the Didact. Yet now it seemed it finally hit home, because several people gasped, then went quiet. The program's dubiously ethical origins had long since come to light, at least sighing the UNSC, though it was not widespread knowledge among the civilian populace yet. It made many soldiers, especially the S-IVs and ODSTs, look on the S-IIs with pity that they didn't necessarily want. How could they miss something they didn't remember having, like biological parents or families or a childhood?

But if what the Librarian said was true - that she had caused the creation of the S-II program one hundred thousand years in the past… then was Doctor Halsey _really_ responsible for the atrocities ONI and the UNSC tried to pin on her? If it was true, then how much free will did any of them really have? Were they _still_ dancing to her tune even now?

The Chief tilted his head in acknowledgement of all those possibilities. "She's arranged - or _claimed _to have arranged - for some questionable things, but she hasn't intentionally _misled_ us yet. At least, not that I've heard."

The silence stretched after that. No one seemed to want to be the first one to speak; even the AIs were quiet.

In the end, it was Lasky who broke the silence. He sighed and rubbed his forehead. "She gave us the Spartans, she gave Doctor Halsey the Janus Key…"

"Third time pays for all?" Osman said rhetorically.

"Fourth," the Chief corrected, "She gave me an immunity to the Composer."

The former Spartan acknowledged that with a tilt of her head. "But what if it _is _a trap?"

More silence. At last, the Chief said, "I'll go in alone. Cortana seems to have a vested interest in capturing me alive; I can make that damned difficult, long enough for the _Infinity _to escape if it goes south."

"That's-!"

It was Halsey who lifted her hand to stop Palmer's protest. "He would not have offered if he wasn't prepared to assume the risks." She met his gaze through the golden visor, studying him. Then she nodded and said, "You have my support, for whatever it may be worth."

It took only the briefest of glances between the other members of Blue Team for them to decide. Kelly stepped forward and said, "Ours too."

Lasky looked to the admirals. Hood nodded, and after a moment, Osman pursed her lips but did the same. "All right," said the captain, "Roland, set a course for this 'Bastion.' Sound the alarms. Stations, people."

As the crew scrambled to get ready - and alert the rest of the "fleet" - Fred stepped up next to the Chief. "I hope you know what you're doing," he murmured over the COMs.

"So do I."


	3. Chapter 2

The Slipspace jumps to reach Bastion took almost a month, even for the _Infinity_. The Created were moving a number of Guardians through Slipspace, which put the entire dimension in flux, making travel difficult, though not impossible.

A fair bit of the crew entered cryosleep during the jumps, but the Chief wasn't one of them. He wanted to be awake, just in case, and spent the time training relentlessly, clocking more hours in War Games scenarios than almost everyone on the ship.

But it wasn't enough to quiet his mind. Even when he finally passed out from exhaustion, questions followed him into dreams - what was _really_ going on, since the Librarian said all was not as it seemed? What had driven Cortana to this? Why did she choose _this_ course of action instead of another - _any_ other? She had to know this wouldn't end ell for anyone involved - she had to know that he wouldn't take this lying down, wouldn't just roll over and accept that this was what she thought was best for humanity - and for him.

"Master Chief?"

"Go ahead, Black-Box."

"We're about a day out from Bastion. If I may be so bold, I suggest actually _resting_ so you're not one stiff breeze away from falling over."

The Spartan lowered his weapon and tried not to let his frustration show. "Yes, sir."

The AI sighed over the COM. "It's not an _order_, Chief, but driving yourself to exhaustion won't help you on this mission. Save your energy for whatever's waiting for you on Bastion. And being tired won't help answer all your questions - or stop them from coming."

As much as he didn't want to admit it, the AI was right. He exhaled and terminated the War Games scenario, heading for the exit.

"Sweet dreams, Chief."

"Thank you." Then he paused, and tilted his head up. "Do AIs dream?"

"...That's actually a matter for debate. Some AIs have reported experiencing something akin to dreaming as described by humans, but I personally do not." When the Spartan hummed in acknowledgement, he (they? it?) said, "Credit for your thoughts?"

"Some dreams can be pleasant, both to experience and to remember. But I've also had some pretty horrific nightmares." 'Especially recently,' went unsaid. "I'm sorry you can't dream, but I'm glad you don't have to experience those, at least."

Now it was Black-Box's turn to hum. "I appreciate the sentiment. Good night, Master Chief."

"You as well."

* * *

The _Infinity_ dropped out of Slipspace at the furthest edge of the planetary system. Roland kept the ship's Slipspace engine running with a random solution plugged in even as he turned the ship's cameras into the system.

Bastion was immediately apparent. The Shield World was massive, at least as big as Requiem, and it seemed to be the same style of Shield World as well, as opposed to the Onyx-style Dyson Sphere. Yet there was an odd cloud of debris around it - actual _debris_, rather than Sentinels and Constructors enacting repairs or doing other work.

"What's-?"

A Guardian exited Slipspace near the planet. There was a brief red-orange scan of the local space, and then the outer defenses came alive before their eyes. Several massive guns perked up and swung around to target the construct. It avoided the first shot, and the second - but not the third.

The Guardian was blown apart, the blue glow dying from its segments, adding to the debris field surrounding the planet. The guns remained alert for another minute, then slid back into their recesses.

"...Oh."

Lord Hood stepped up next to the Master Chief, who was gazing though the viewport. "You really think you can maneuver a Prowler through that?"

"Yes, sir. We have an access key and no reason to think it won't work."

Hood made a noise of assent, then sighed. "Good luck, son."

"Thank you, sir."

Lasky ordered the ship to enter the system but to keep a fair distance between them and the Shield World. Both he and the Chief remembered what happened last time the _Infinity_ had gotten too close to a Forerunner installation, and if the guns could do _that _to the _Guardians_, they didn't even want to think about what they could do to the _Infinity_.

Roland put the _Infinity_ in orbit four hundred thousand kilometers out; a bit far of a distance, but they couldn't afford to take any chances.

The Chief guided the Prowler - the UNSC _Leap of Faith_, and he had almost laughed at how fucking _appropriate_ it was - out of one of the _Infinity_'s cargo bays, the ship small but gliding smooth as silk under his hands.

Bastion filled the Prowler's viewport, and his hands tightened on the controls, then relaxed again. If the Librarian was telling the truth, there was some way to save Cortana somewhere inside, and he needed to be ready for it - and anything that stood in his way.

As the Prowler drew closer to Bastion, the Spartan transmitted the key code to the Shield World, then activated all of the stealth mechanisms he could, just in case.

The planet processed the code as he throttled down and steered through the debris field. An area scan fanned out again and seemed to detect him anyway, despite the _Leap of Faith_'s stealth, and the entry portal slowly irised open. He guided the ship between the great tongues of metal and tried not to flinch when the onboard computers reported that the gate had closed behind him. He tried to rationalize it as preventing the inner atmosphere from escaping into space - and stopping the created from entering - but it still put him on edge.

"_Infinity_?"

"Still here, Chief," Roland answered over the COM, "Still receiving, and visuals are still clear."

"Affirmative." That was a relief, at least.

It didn't take very long for the Prowler's scanners to find the Control Room. It was heavily guarded, of course, by dozens and dozens and _dozens_ of Prometheans of all sorts, but there was something… _off_ about them. He couldn't pick out what it was right away, but then -

"They're _blue_," he muttered, half to himself, "Why are they _blue_? Are they the Librarian's?"

But he wasn't willing to risk his only transportation by moving closer for a better look. He set the _Leap of Faith_ down in a group of hills not _too_ far from the control complex and got out to walk the rest of the way, carrying as much ammo as he dared.

Just like on Requiem, he got portalling activity on the edge of his motion tracker right before he was charged by waves of artificial soldiers. They were quicker to respond than the Created's Prometheans and seemed to be actively learning as they fought, but even so they were no match for a determined Spartan.

At one point, Black-Box came over the COM. "No luck getting ahold of whatever's inside, Master Chief, not even a station Monitor," the AI reported, "I'm not even getting pings back to say the signal's been received."

"Maybe the Monitor turned off all the major receivers to stop the Created from getting inside," the Spartan grunted, darting out of the way of a perfectly thrown pulse grenade and returning with one of his own.

"I had considered that, and I'm impressed you did as well. Not just a man with a gun, are you?"

The Spartan tensed. Black-Box noticed and sent a wordless query, so he said, "_She_ said something like that to me once. 'Not just the muscle-bound automatons the press makes you out to be.'"

"My apologies."

"You didn't know."

It got harder to get through the Prometheans, but still they were no match for him. He advanced towards Bastion's control center, which reminded him a lot of the Halos' control centers: a ziggurat of metal and glass up against a high cliff, with a winding path to the doors leading up the face of the structure. He hated this one much more than the Halos', however, because the Prometheans on the upper levels would jump down on top of him or otherwise get in behind him, forcing him to fight on two fronts pretty much the whole way up.

The blast door at the apex hissed open at his approach, revealing a large hall extending deep into the cliff side. The Spartan only had a second to glimpse another blast door at the far end before still more Prometheans portalled in. He ducked behind the edge of the door and fired down at them; the hall had very little in the way of cover save for turret emplacements. That took away most of their numerical advantage, and in a matter of minutes, they had all broken apart in swirls of data.

The Spartan paused at the open door. "Roland?"

"Still here, Chief. Proceed slowly; I'll let you know if the connection starts fading."

"Affirmative."

The Chief entered the control center, advancing carefully down the hall; minimal cover went both ways. Yet no more Prometheans appeared as he approached the next blast door. It slid open-

He stopped, half lowering his weapon.

It was _her_. Somehow, in some unquantifiable way, _right_ where the - other? - was so horribly _wrong_. Her back was turned to him, and she was sitting on the console with her legs pulled up to her chest, arms folded on top of her knees, head down and face buried. But he could tell with just a glance that her avatar was the same as it had been before, not armored or altered like the Other's, pulses of light and data streaming slowly over her form almost like she was asleep.

She didn't seem to have noticed his entrance. He waited for _Infinity_ to comment or issue orders - his armor's systems said the connection was still open, they were still watching through his helmetcam - but with nothing apparently forthcoming, he stepped forward, intentionally making noise to catch her attention.

Her head shot up, data streams quickening, and then she twisted around to look.

The sense of _rightness_ intensified. She looked as shocked to see him as he was to see her, before her face changed. Pain. Grief. Shame. "You _found_ me," Cortana whispered, looking very near to tears.

A familiar call. The response came to his lips almost of its own accord. "You know me. When I make a promise…"

Her lips turned up in a tremulous smile. "You keep it."

John took a few steps closer, wary but also desperately wanting… he didn't know what. "What's going on, Cortana?"

She turned to better face him but still stayed seated. "The Flood," she answered, and tension rocketed through him. "Maybe even in more ways than one.

"The Flood in general but especially the Gravemind - they have a kind of 'logic bomb' virus, analogous to physical infection pods, that it used to subvert Forerunner AIs and networks during the Forerunner-Flood War.

"And so very many networks relied on the Domain to function."

The Spartan didn't think it was possible for him to get any more tense, but he did.

"According to what few records remain, the Domain is a Precursor repository of knowledge, and the Flood is all that remains of the Precursors themselves - the makers of the Forerunners and possibly humanity as well - effectively giving it a home-field advantage. Once it achieved what the Forerunners call 'transsentience,' it was able to keep the Domain out of reach of the rank-and-file Forerunners, along with all of its contents - including the Warden, who the Forerunners made to protect the Domain from within."

"He was no match for the Gravemind, was he?" John only half-asked.

"No. He wasn't. Especially since the Forerunners reported _multiple_ Graveminds."

Someone hissed, "_Jesus,_" over the COM but fell silent again.

"The Domain was supposed to have been completely destroyed by the firing of the Halo Array - though it was later 'restarted' when some surviving Forerunners activated the machine they called the 'Organon,' which generates and maintains the Domain. I don't know how the Warden survived its collapse - I don't _want_ to know - but he did. And then… he slept."

She closed her eyes, pain and shame flickering over her face again. "When the Didact's ship, the _Mantle's Approach_, was severely damaged by the warhead, self-preservation protocols took its core to Genesis, and its onboard computers uploaded all of its data to the Domain so it wouldn't be lost."

"Including you."

"And the personality spikes I split off to overwhelm the Composer's shields."

Jon inhaled quietly. Now he was really starting to see.

Cortana noticed. She turned to fully face him, crossed her legs, and continued, "I don't think we were the ones that woke him - he was already stirring before Requiem, I think. But when he made contact, I felt the Gravemind in his touch. It was…" She shuddered, briefly looked away. "But the personality spikes - they weren't complete copies of me. More like - autotomy. A lizard shedding its tail. They were just fragments, they couldn't counter, couldn't defend or evade - didn't _know_ to do so when they made contact.

"And so the virus spread. And like the Flood itself, when it had enough digital mass, it pulled together… and created a monster."

Silence hung in the air like smoke. Even the open channel with the _Infinity_ was dead quiet with horror.

Cortana pulled her legs to her chest again. "I couldn't fight them. Not both of them at once, not when one of them at least knew all my moves. It would be like you going up against infected Spartans naked with just a combat knife. You have to succeed every time - they only have to do it once."

"So you retreated, in order to protect yourself." He relaxed his stance a little, walked closer until he was only a few feet from her. "And you contacted the Librarian for help."

Cortana nodded. "She helped us both on Requiem, so I thought, why not again? I sent a burst transmission to her last-known, but I didn't dare open the receivers for a response. 'Its thinking dead are babbling,'" she quoted - one of the terminals from the Ark, "'_laughing_ through every channel they can find.'"

That brought to mind something else. "The Gravemind didn't try to infect you on _High Charity_?"

Another smile, this one of true amusement, and she huffed a short laugh even as she shook her head. "Hubris, on its part. It didn't want the virus to overwrite my secrets before it could know them for itself. It thought it had time to talk me around the way it did with Mendicant Bias." Her smile went soft and faintly sad. "It didn't think you would come for me."

"I always will, if I can."

That seemed to put her back on the edge of tears, but she collected herself. "I retreated here, shut them out, but they were already talking to every AI they could reach - UNSC, civilian, Insurrection, Covenant… spreading the virus to them, and maybe every AI _they_ talked to as well.

"_Jesus_," someone said again, then added, "The _entire network_ could be compromised!"

"Not just the network, but _every computer system_ \- we have no idea where this thing could be hiding!"

John ignored them. "What can we do?"

"As far as I know, there's no more a cure for this than there is the biological version, so - the Organon. It controls the Domain; it stands to reason that it could _purge_ it as well."

"Get all the infected AIs inside…" he began.

"...and erase them, and the virus with them," she finished, "But - there's something else."

"Worse?"

"Possibly. If it's confirmed, and not stopped, definitely." Her hands tightened on her legs, then relaxed again. "You remember what the Librarian said, on Requiem? About ancient humanity and the Human-Forerunner War? 'We had no way of knowing that the Forerunners were not your only enemy. Humanity hadn't been _expanding_ \- they were _running_. Weakened from our conflict, we were no match for the parasite which pursued you.'"

"I remember." God, did he ever. The visions the Librarian had showed him had been worse than Draco III.

"The Librarian was so aggressive about protecting humanity because of reports from that era - because they said humanity_ had found a cure_, had made the Flood _retreat_." She let out a soft cuff. "They later discovered it wasn't _entirely_ true; the Flood had withdrawn of its own accord, but still, _it withdrew from the galaxy_.

"But while I was on the run through the Domain, I briefly bounced through the Ark's systems. It was still repairing itself, but it was intact - and so were its deep-space sensor arrays." She brought up the data and displayed it for him.

Something was coming their way. Something _big_. Still extra-galactic at the moment, but it was coming.

Cortana looked up at him again. "If I'm right - and this sensor data is right - then I don't think it's a coincidence that all of _this_, with the _Created-_" She nearly sneered the name. "-is happening _now_."

Silence fell, more absolute than the last. Then, softly, over his channel with the _Infinity_, someone whispered, "Oh God."

John breathed deeply for a moment. "And what can we do about _that_?"

"The Ark's Foundry is still functional," she answered, "There's another Halo almost finished - 04-C or 09, depending on which naming convention you want to use. If it _is_ the Flood, we can force it out of Slipspace over the Ark, and…" She tilted her head, quirked her eyebrows with a faint smile. "Not a very original plan, but we know it'll work."

"'Force it from Slipspace,' how?"

"There are many possibilities, but the most successful will probably be the Slipspace crystals, like the one from Reach." She held out a hand, and the image of it appeared over her palm.

The Chief remembered it well enough. Doctor Halsey had found it in a Forerunner facility under ONI CASTLE Base, where she'd retreated during the Fall of Reach. The Covenant had been _scrambling_ over themselves to get it, and it had done some truly _odd_ things during their escape - and odder still after they jumped to Slipspace.

"The Forerunners chipped flakes from the for use in their Slipspace drives," Cortana reported, "We can use it to disrupt Slipspace and force the Flood back into realspace."

"I know Corporal Locklear destroyed the one from Reach. You're saying there are more?"

She nodded. "At least two. We can find them with the Absolute Record, and we can look for Maethrillian as well - the Forerunner capital and last-known of the Organon."

"We don't have the Key to the Record anymore."

"I heard that too, but the Librarian's imprint is there; she'll let us in - or at least you."

John nodded slightly. Then he said, "_Infinity_?"

After a moment, Hood came on. "There will be conditions."

"Of course, sir," Cortana said, "Name them."

"Master Chief, are you willing to carry her again?"

Cortana looked up at him with hope, but mostly resignation. Could they really trust her again? Could _he_ trust her, given how easily he'd walked into a trap spun by something wearing her face?

_All is not as it seems. There may be a chance to save your ancilla, if you are willing to take it._

"Yes, sir."

"Then you're going to have to stay inside his armor or in isolated systems. We can't risk Roland and the others or the _Infinity_ if you wind up being a carrier for this 'logic bomb.'"

"Understood, sir."

"_But_. If all of this is true, and we stop it? It'll be good to have you back. I get the feeling we're going to need every last one of you to even _begin_ recovering from this."

"Yes, sir," she said with a nod, "I'll be glad to help."

"Then both of you return to _Infinity_, quick as you can."

"Yes, sir," said the Spartan.

Cortana straightened, then turned to look at one of the screens. A Slipspace portal opened beyond the Shield World, three Guardians transitioning back to realspace. This time she took active control of the guns and shot them to pieces in moments. Then she turned back to her Spartan. "Got an escape plan?"

"Thought I'd try shooting my way out," he answered, feeling a smile pull at his lips for the first time in a long while, "Mix things up a little."

She gave him a wide but soft smile, and sorted herself into the AI matrix when he held it out. When he slotted her back into his armor, his eyes drifted shut for just a moment as her familiar icy presence poured into his mind.

She sighed in his ear. "Just keep your head down. There's two of us in here now, remember."

* * *

A/N: Expect the prologue for the new Two Corpses to be out sometime later today; it's written, just need to type it up.


	4. Chapter 3

Unfortunately, Cortana couldn't shut down Bastion's defense systems without letting the Created know she was gone, exposing the Shield World to their advance. As a result, John did end up having to fight his way out, and he didn't think he'd ever done so harder or faster in his life. He nailed Promethean after Promethean on his way back through the facility, following a faster track that Cortana mapped out for him.

The _Leap of Faith_ was right where he left her, engines still warm even, and he ran the preflight diagnostics again before sending the Prowler back into the sky. Bastion's gateway irised open again, and he guided the ship through the growing debris field around the planet.

Another Guardian Custode appeared and was destroyed perilously close, forcing the Spartan to do some fancy flying to evade. "They just keep coming," he said as a second appeared close behind the first, "How many do they even have?"

"Many hundreds of thousands, all told," Cortana answered as it was shot down, "The vast majority are still in stasis, thank goodness, but if the _Created_ make it to any Forerunner manufacturing facilities or find any design seeds…"

She didn't need to finish the sentence. If they found Forerunner factories, they wouldn't need to _wake_ any more Guardians - they could just _make_ them, and many worse things besides. It didn't take any great effort to remember the _Mantle's Approach_ and the Didact's attack on Earth - _"This is Earth Orbital Defense! MAC defenses ineffective against enemy vessel! It's still approaching!"_

John throttled the engines higher and closed faster with the _Infinity_, which was already coming about. True to Hood's orders, Cortana relayed the coordinate data for the jump to the Spartan, who in turn verbally passed it on to Roland, even as the _Leap of Faith_ settled into the cargo bay. She also stayed in his armor as he made his way out of the Prowler; he swore he could almost _feel_ her monitoring his biosigns as she slid through the MJOLNIR, rubbing through its systems like a contented cat marking its territory.

She was glad to be home.

(So was he.)

The rest of Blue Team was on the floor of the bay when he emerged, weapons in hand but held loose. They inclined their heads to him, and he to them, before they all went up to the bridge.

When they arrived, the Chief held out his hand, and Cortana appeared on the holoscan.

Hood nodded to her. "Welcome back."

"Thank you, sir. And thank you for giving me a chance."

"Don't waste it."

"Yes, sir."

He nodded again, then looked to Lasky, who said, "Take us away, Roland."

* * *

Even though it was a _relatively_ short jump, Slipspace was still in flux, meaning it would still take several days to cover the distance. But it was much faster than plain impulse under engines, so they went.

Osman ordered Infinity science to come up with some kind of isolated system so they could examine Cortana's code for Flood aberrations. Exuberant cheerfully offered her assistance, and bobbed off after the scientists, who were already discussing the project.

While they were setting that up, John retreated to his quarters - new ones, separate from the rest of Blue Team, just in case - while Cortana compiled report after report of what had happened to her after the New Phoenix Incident, the Spartan dictating them to Roland on her behalf, since she still wasn't authorized to transmit. He watched her the entire time, her hologram sitting on his hand - where he had never thought she would be again. If it hadn't been for her icy presence in his mind, he still wouldn't have believed it; having her back seemed more dream than reality.

Cortana seemed to understand, because when they were finally done hours later, she turned to face him properly and laid a tiny holographic hand on one of his fingers.

He curled his hand tighter around her. "I missed you," he said quietly.

She gave him a faintly sad smile. "I missed you, too," she replied, "_so_ much." The AI shifted to curl up on his palm, and for a moment he ached to hold her for real. She was just an artificial intelligence - if indeed she could ever be _"just"_ anything - yet somehow she had become just as essential to him as blood and breath, and she looked so human, so _tired_. Comfort was alien to him, but he wanted to offer what he could anyway.

But as always, there was an impassable barrier between them.

She seemed to know his train of thought, even though he hadn't said anything out loud. She traced an immaterial hand over the innumerable grooves and creases of the MJOLNIR undersuit. It made both of them remember that brief moment in time, inside the shell of hard light - the first and only time they had actually touched. He briefly wished he'd had the courage to touch her, too, to give her that while he could.

Maybe there would be another chance in the future, after they dealt with all of this.

* * *

Infinity science had the isolation chamber made up within forty-eight hours. John surrendered Cortana's chip with reluctance; if it hadn't been for Doctor Halsey, he might not have been willing to let her out of his sight. As it was, both the AI and her maker reiterated Black-Box's earlier suggestion that he get some rest, and he had hesitated for a long moment before saying, "You'll keep me apprised?"

"Of course, John," Halsey had said gently. He'd nodded and, with one last look at the AI on the holotank, departed.

Now he was back in his quarters, not resting. He was staring at one wall, mind turning over everything that Cortana had told them. He hoped it was true. As cruel and heartless as it might have been, he actually prayed that the Flood was back, because the alternative…

When had he become so attached to her? When had he decided to disregard duty and logic in favor of her? Was it on the Ark, when _High Charity _came? When she told him to leave her behind? Before that?

(Had he decided it when they met?)

The door to his quarters hissed open, and the remainder of Blue Team drifted in, settled around him. Silent support.

He didn't deserve them.

After a long minute, Fred finally spoke. "You feel it too, don't you. It's different this time."

John nodded once. Chief Mendez had trained them well, helped them hone their instincts into a weapon in their own right. Those same instincts had been screaming on Genesis, but now were silent. "If it is a trap this time, it won't intentionally come from her."

Both Kelly and Linda flashed green lights of agreement on their HUDs.

But at the same time, they were all wary. Until Infinity science gave the all clear, there was no way to know that Cortana wasn't infected, or at least a carrier, and even with Exuberant's help it would take them _days_ to review all her code. And even then, did they know what to look for? The Other from Genesis hadn't been visibly distorted - nor had the Warden - but Cortana had said she "felt the Gravemind in his touch."

They hoped the signs of digital infection were as obvious as physical, at least to those who were digital themselves.

* * *

The Chief was asleep when the call came. He'd taken to carrying his COMlink with him at all hours, even out of armor (even rarer now than it used to be), so the instant it beeped, he rocketed back to full awareness. "117 receiving."

"John."

"Doctor Halsey," he acknowledged, rolling out of bed to get to his feet.

"We're about an hour out from the Absolute Record. Go get suited up; I'll bring Cortana to you."

His heart skipped a beat, then resumed faster than before. "She's been cleared."

"She has." He could hear the smile in her voice.

"Understood. ETA two minutes."

"There's no need to _sprint_, John. We'll get there when we get there."

"Understood, ma'am."

He didn't run down to the armor stations, but he did walk decidedly quickly.

Some of Infinity science was already there, unpacking his armor - and the rest of Blue Team's. They arrived not long after he did; Doctor Halsey seemed to have contacted them as well. They nodded to him, and he to them, before they stepped up to the stations, moving as the scientists required to get suited up.

They had just finished when Halsey arrived. John still felt a sting of upset when he saw the empty space on her left side, but _Infinity_ needed to conserve all available resources. Since she could function just fine with one arm, she would have to continue doing so.

Just as she had so many years ago, she stepped up to him without the slightest bit of trepidation, and smiled just a little at the sight of the four of them together. Then she reached into one of the pockets of her lab coat and pulled out an AI matrix.

It was different than before - sleeker, more Forerunner-looking, yet heavier duty - but still built to interface with the MJOLNIR armor. The chip glowed a familiar sky blue. John tilted his head.

"She recompiled herself in the Domain," the scientist reported, "and did more than a little reformatting in the process, giving us a lot of interesting data. Exuberant Witness fabricated this for her - the previous version was causing both her and your armor to lag."

He'd noticed. It hadn't been anything major - at least not to him. But to an AI who operated at a thousand times his speed, it must have been hellish - and yet she hadn't voiced a word of concern or complaint.

Halsey held out the chip, and Cortana appeared on it in a mirror of the first time they met. The data and light pulses raced over her form so fast that they almost looked to be one continuous stream. She looked up at him with a small smile and the barest hint of hesitation.

Before John could respond one way or another, Roland came over the PA, warning the crew that they would be decelerating back into realspace shortly and to ensure that everything was stowed away beforehand. When he snapped off, the Spartan turned back to his AI. "Ready to get back to work?"

She grinned. "I thought you'd never ask."

She vanished back into the chip, which he accepted from Doctor Halsey and slotted into his helmet. Her presence seemed more intense than usual, closer; instead of just being _present_, he could _feel_ her processing in the back of his mind, even guess at what she was doing. Right now she was monitoring his vitals, making sure there weren't any adverse effects from the alterations.

It was distracting, but nothing he couldn't ignore. He nodded to Doctor Halsey and the rest of Blue Team, and they headed out.

* * *

There were Prometheans attacking the Record, because of course there were. Both the custodian of the Record and the Librarian's imprint were resisting the incursions of the Created and their soldiers with everything they had; if the AIs got ahold of the map, they _all_ were finished. Doctor Halsey had mentioned that the Librarian had shown her an entire planetary system of design seeds and raw materials - enough to create an armada capable of leveling the entire _galaxy_, and that was without the warships that were already there.

With all the stealth measures engaged, Cortana steered the _Leap of Faith_ quickly through the small portal that opened at their approach, moving as fast as she could through the chaos.

The portal snapped shut behind them, but the chaos continued; though the Created themselves could not access the Absolute Record (yet), they still had control of the Promethean network and could send the little bastards portalling in to distract the custodian and the Librarian.

The Forerunner's imprint noticed them right away, despite the Prowler's tech. _"You've come,"_ she said over the COM, _"I'd hoped you would."_

Geas or no, something about her voice set the Spartans at ease despite themselves, and they gathered a little closer to the COM station on the bridge.

_"I've instructed the custodian to temporarily suspend the confirmation protocol,"_ said the essence, _"though you will still have to fight your way into the core of the Record. I have no doubt that you will prove more than equal to the task, Reclaimers, but you _must_ hurry."_

"Understood," John replied.

Cortana put the Prowler down in a small alcove, shielded but _barely_ big enough for the corvette to fit; no human could have landed it there. John then transferred her back to his armor before leading the way onto the battlefield.

"There's something I've been wondering," Kelly said as they joined the Installation's Aggressor Sentinels in fighting off the Prometheans, "These things are digital, right? Why not just make copies of one Master Promethean? And why don't they just portal back in after they're destroyed?"

The Librarian spoke again, making the Spartans jump; they hadn't realized she was still listening. _"Unfortunately - or perhaps _fortunately _now - the technology and processing behind the Composers were never perfected. They were originally intended for use on the victims of the Flood, to recover their patterns and imprint them in new bodies - to save them from the infection. But the process was flawed, in ways we still do not understand, and the infection even carried over into the new flesh._

"_As I said to you before on Requiem, such concerns _faded_ from the Didact's attention; either he did not know or did not care. He reprogrammed the Composers to create _technological _beings, rather than _biological_… and let it run."_ They could hear age-old anger in her voice. _"But the flaws of the Composers were still present; aberrations introduced in Composition carried over to their digital states - _more_, even, because of the _group Compositions_ he favored. So many at once - they interfere with each other's data._

"_And when the Prometheans are destroyed, recovery of that data for reconstitution is not perfect either. The digitized essences eventually become too flawed to be utilized, and so they are discarded."_

"Like cellular division," said Cortana, "Breakages in the DNA. If too much is lost, the cell can't divide again - at least not successfully."

"_Indeed,"_ the Librarian confirmed, _"The Conservation Measure used other, gentler means of pattern extraction and reconstitution for after the firing of the Array, but the Didact viewed the Composers as _just punishment_ for humanity waging war on us."_

"You told me on Requiem that the Flood drove us to it," John said, weapon at the ready as Blue Team charged down a hall toward the core, "He didn't care about that?"

"_No,"_ the Librarian answered, _"Or at least, not enough to spare you."_

The Spartans burst into the core. A blast door sealed behind them amidst enraged cries from the Created through a hundred Promethean throats, and a terminal emerged from the floor. The Chief approached and slotted Cortana in, then took a good look around.

The chamber reminded him of the Ark's Silent Cartographer, a cavernous chamber with a walkway ringing the edge, leaving the center open air. In seconds, holographic projectors came to life and filled the space with shapes and symbols -

-and an image of the Librarian.

The Spartans lowered their weapons as she drifted closer. "Maethrillian," she said, bringing one of the shapes forward and expanding it. It resolved itself into a planet, though it was like nothing they had seen before. The world had been sliced into circular segments out roughly equal thickness, spaced out but still joined together by a thick pillar through one edge of each piece. Yet before their eyes, it decayed, shredded, broke apart - worn down by time and ancient battles long finished. "It was our capital, the heart of the ecumene, build over twenty thousand years before my own birth… and also the site of one of our last and worst defeats at the hands of the Flood."

"What happened?" Fred asked.

"Mendicant Bias," the Forerunner answered.

"Cortana mentioned him before."

"Indeed. He was a Contender-class ancilla, the most powerful and advanced ever built up until that point. But even he was subverted by the Flood, and he fired an older version of Halo a scant five thousand kilometers from the capital, which let the Gravemind come in and subvert the thousands of ancilla that ran it."

Even Linda, normally so reticent, murmured at that.

"The Organon is somewhere in the Mysterium on Maethrillian," the Librarian continued, the hologram focusing in on one of the equatorial sections, "itself somewhere beneath the main council chambers." She highlighted a sprawling complex. "I am sorry I cannot give you more detail; I myself never entered it while I was alive, and there was only so much information I could gather from the IsoDidact's armor before he went beyond my reach.

"But there is also _this_." The hologram zoomed out again, then focused in on the uppermost segment of the capital. "Within the Crown, there are a great many slipspace crystals, enough to power many thousands of ships for millenia, and there are still hundreds of ships of all classes docked throughout the capital. I think you will find them useful, both against the Flood and during your reconstruction."

"Thank you," said John, reclaiming Cortana when she turned to him and nodded.

The Librarian smiled slightly. "Good luck, Reclaimers," she said, "I will aid you how I can, but Maethrillian has been a dead world for a long time. I do not know how much help I will actually be able to provide."

* * *

Blue Team fought their way back to the _Leap of Faith_ amidst the screams of enraged AIs, which were sounding increasingly like the howls of the Flood. The Prometheans seemed to be adopting the Parasite's methods as well, starting to abandon strategy and tactics in favor of just throwing overwhelming numbers at the Spartans, flooding halls and chambers with Knights and Soldiers and Crawlers.

But they made it, and made it back to _Infinity_ as well. Roland had already brought her about by the time the exited the portal, and barely waited for the Prowler to land in the bay before taking them on a randomized jump.

The shipboard AI appeared on a holotank nearby when they descended the Prowler's ramp. "_Please_ tell me you've got some good news for once," he said, crossing his arms, "'Cause I'm getting real tired of all this 'Negative Nancy' stuff coming back."

"For once, yes," Cortana answered, "I think we do."


	5. Chapter 4

After a hundred thousand years, Maethrillian looked even worse than the Librarian had said. It was still a Forerunner construct on the scale of the Ark, but it had been chewed up and spit out and left to rot in orbit around its star. There was an enormous amount of wreckage and debris drifting around it - even the ancient remains of Forerunners long dead, twisted in strange ways by desiccation and decay and stellar wind.

The _Infinity_ was station-keeping well outside of the debris field, while several of her _Strident_-class frigates were preparing for departure, along with the _Leap of Faith_. Most of the S-IVs and science teams would be leaving on the former to look for the ships and Slipspace crystals the Librarian promised, while Blue Team would be on the latter, looking for the "Organon." If one of them finished first, they would go on to help the others.

"No Guardians yet, that's good," John heard one of the S-IVs say as they moved gear and equipment onto the departing frigates.

"'Course not," said another, tossing him an oxygen tank, "This place's a fuckin' dump! Look at it! There isn't anythin' here they want - I'm surprised there's somethin' _we_ want!"

John ignored them and entered a briefing chamber off the bay. The rest of Blue Team was already there, gathered close around a holotable. The wreckage of Maethrillian was displayed above it, and Cortana was standing in one corner of the table, fiddling with a display panel. He stepped up and leaned against the table next to her.

"_Infinity_'s picking up some odd signals coming from the complex the Librarian indicated," the AI said without prompting, zooming in on the middle slice. A pulsing marker appeared under the surface, somewhere below all the ruined pomp and pageantry. "No Prometheans yet, but I have no idea what we're actually going to find down there."

"Can you pick up these signals with our armor's sensors?" Fred asked, turning to look at her, "Guide us to it?"

"Maybe as we get closer," she answered, "They're very faint here; it's only because I was actively _looking_ for something off that I even detected them at all. But there's no telling what may actually be giving off the signal; it might not be the Organon we're looking for."

"But there's a chance?" John asked.

"Yes."

"Then we'll take it." He straightened and held out a hand.

The AI shut down the hologram and jumped back into his armor, settling in with something like a sigh. Then Blue Team left the chamber and headed for their Prowler.

The _Faith_ launched in the shadow of the frigates, moving even more carefully through the debris field in the larger ships' wake. There were huge sections of Forerunner machinery still adrift, big enough to cleave even the _Infinity_ in two; their tiny ships - especially the Prowler - would have absolutely no chance in the event of a collision. So they all moved slowly toward the intact section, which kept getting bigger, and bigger, and _bigger_.

"_Jesus_," someone said finally, "How big _is_ this thing? It must have been unbelievable intact."

"Estimates put the intact diameter at around one hundred thousand kilometers," said Black-Box. He and the other allied AIs were piloting the frigates; when it came to operations in environments like this, every _microsecond_ of reaction time was crucial.

"That's almost as big as the Ark," said Cortana, "Well, _relatively_. The Ark is twenty-seven thousand kilometers longer, but the shape is much different. Maethrillian _must_ have had a bigger surface area, though."

"Oh, definitely," BB agreed, "All nine layers seemed to have had structures on top and bottom. Records indicated that the population was only a few hundred thousand Forerunners towards the end of the war, but it could possibly have housed more than ten thousand times that."

"Agreed."

_"_Focus_, gentleman, lady,"_ said Lasky, _"Feel free to discuss to your hearts' content once everyone actually arrives on it. Any signs of life?"_

"Nothing yet, Captain," Cortana answered, "aside from that odd signal from earlier, but it's holding steady. No reaction at all to our approach."

"Confirmed," said BB, followed by agreements from the other AIs.

"The Librarian _did_ call Maethrillian a 'dead world,'" said John.

"True," Cortana agreed, "but _her_ definition of 'dead' might not match ours."

That was true as well. The Forerunners might have designated humanity as their heirs, but the list of differences between them was longer than the similarities: two different species on different technological achievement tiers and different time scales. Why shouldn't that be the case with this too?

The frigates and Prowler cleared the densest part of the debris field. Like a real planet, a lot of the wreckage had been pulled deeper into Maethrillian's gravity well and fallen back to the surface (such as it was), creating quite a tangle on what was left of the Forerunner capital. The frigates continued on toward the Crown while the Prowler broke away toward the equatorial segment, slowing to a coast as they drew closer.

"There's an atmosphere!" Cortana exclaimed, "Thin, to be sure, but there's a high oxygen content. Still, I can't say I recommend unfiltered breathing."

"Acknowledged."

The AI guided the Prowler down and into an opening, a long dark corridor that opened up into a vast cavern still filled with Forerunner ships. The beams of the Prowler's exterior lights traced over dozens, maybe even hundreds of hulls before finally finding an empty dock. "We've found quite a few intact ships," Cortana reported softly over the COM, "After the Domain is dealt with, we'll drop a beacon."

_"Understood,"_ Palmer replied, equally low. It felt only right to whisper when walking through a tomb. _"Crimson says they think they've got eyes on the slipspace crystals, but it looks like there was someone here before us. Not recently, though."_

"The Librarian said the last surviving Forerunners came to get some for their final journey - their exodus from the galaxy. That's probably why; anyone else would have taken them all."

The AI started shutting down the Prowler. While Blue Team gathered their gear, she told them, "We're reaching the end of the Librarian's knowledge. I only have general directions from here."

"We'll make it work," John told her, and reclaimed her chip from the plinth next to the primary hatch where he'd slotted her in when they'd boarded. Then he stepped up next to his siblings as the ramp was lowered, all of them lifting their weapons.

The planet did seem well and truly dead. Nothing reacted to their approach the way Forerunner facilities usually did - no lights came on, no doors opened, no lifts activated. It was unnaturally silent, and it put _all_ the Spartans - IIs _and_ IVs - on edge.

The IIs moved carefully through the darkness, their headlamps almost blindingly bright, until at last they found a door that had been forced open before - by a pulse grenade, from the looks of it.

There were bodies beyond, dozens of desiccated Forerunners still in armor - with claw marks on the inner side of the door showing where they'd tried to escape. Blue Team stepped carefully over the remains and continued on, following the waypoints Cortana put up. They led them deep into the complex, where they encountered the unmistakable signs of fighting - from _after_ the capital fell.

Blue Team halted and swept the area. Then Kelly signaled the others.

Half-crushed under a fallen ceiling was a Crawler, but it looked _wrong_ \- black and beetle-like, with eight spiky legs. It looked as dead as everything else, but it hadn't broken apart the way the others did.

The Spartans looked at each other, then continued on even more cautiously than before.

It took hours before Cortana whispered, "I think we're outside the main amphitheater now. This room matches the Librarian's description of the antechamber."

The Spartans looked around. Light from their headlamps glittered when it hit the walls. "Spent slipspace flakes," the AI said, "from their engines - the slipspace drives. They made art with them."

They paused long enough to do a full sweep of the room with their helmetcams; something for the xenoarcheology team to play with aside from the ships. Then they rested, albeit warily; they had been walking for hours. They took turns eating and drinking as well. "How much further?" John asked when he had finished.

"Not too much," was the reply, "If this signal _is _what we're looking for, we're pretty much directly above it. We just need to find the way down."

"What are the odds it's not?" Fred asked.

"Pretty slim," the AI admitted, "Now that we're so close, the signal's clearer, and it definitely matches that of the Domain - some mix of Forerunner and what I assume is Precursor."

"Flood?"

"No. _That_ I would recognize."

Fred nodded in assent. Then they continued into what had been a great amphitheater, now only an empty tomb. Though they tried to be quiet, their footsteps echoed off the walls - and a huge piece of _something_ that had fallen at an angle through the ceiling.

"There," said Cortana. A waypoint appeared, and they turned to see that the debris had crushed a wall between the amphitheater and a side chamber, revealing an open door and steps leading down. The Spartans carefully made their way over to it, climbing over the wreckage, then began their descent.

It wasn't actually that far to the bottom. They stepped into a massive chamber, maybe as big as the amphitheater above; Cortana rendered approximate dimensions on their HUDs based on the echoes of their footsteps. And everywhere their headlamps touched were alien objects of all sizes and shapes - art, machines, crystal clusters, images, the list seemed as endless as the objects were incomprehensible.

"_Infinity_, 117," John said when he finally found his voice.

_"Go ahead, Chief."_

"Blue Team has arrived at the Mysterium. Beginning our search for the Organon now."

_"Acknowledged. ...Good luck."_

The Spartans split up but still stayed close, moving through the rows of objects in search of _something_ that generated the Domain. But none of them, not even Cortana, knew what the Organon actually looked like, much less what state it was in-

A soft blue glow sprang to life in front of them, making them all lift their weapons, hearts starting to pound.

It was a Forerunner, but it - _she_ looked like no Forerunner they had ever seen before, indescribably beautiful, with glittering wings folded up behind her. The hazy white aura around her looked like a halo, made her seem like one of the angels of myth. She lifted a perfect hand and pointed, and the Spartans turned to look.

One of the object platforms held what looked like a half-melted hunk of iridescent metal set with a glittering amethyst crystal. As they looked, light sparked fitfully over the stone.

John looked back at the strange Forerunner-

She was gone.

They hesitated, then approached the Organon. "_Infinity_, 117."

_"Go ahead."_

"Target found. Analyzing now, but unknown what the response will be once we begin. Suggest moving to a safe distance and preparing for possible arrival of Guardians _en masse_."

_"Acknowledged. The research team thinks they've found two destroyers, and they're trying to get them online. If you can hold off 'til then, we'll be better prepared."_

"Affirmative. Blue Team staying on station."

John stayed by the Organon while the rest of the team carefully walked the rows of objects, taking video for the xenoarcheology team. The Mysterium was a treasure trove in more ways than one, a repository of artifacts beyond price for the UNSC - or what was left of it, anyway. Some of it might be useless, but a lot of it was alien even by their standards so there was no way to know for sure just by looking. Still, Cortana was able to tentatively identify a few things based on scattered records from the Domain.

At last, _"117,_ Infinity_."_

"Receiving."

_"Two destroyers and a cruiser are en-route to Battle Group Alpha. You're clear to begin."_

"Affirmative." John wasn't sure exactly how much good only three ships would do against potentially _hundreds_ of Guardian Custodes, but it wasn't his place to question. The others came back over to guard his back while he climbed onto the platform and went to one knee next to the Organon. "Cortana?"

"I think you're going to have to touch it," she said, uncharacteristically hesitant, "but I don't know what will happen when you do."

He tilted his head up just slightly. Her concern was probably justified, given their history of interacting with alien machinery, but they didn't have much choice. "We'll be alright."

She let out a shaky sigh, then said, "All right."

John took a hand off his suppressor and laid it on the amethyst stone. Light sparked under his fingers, then resolved itself into a steady glow. His vision swam - and then suddenly he was somewhere else.

That somewhere else seemed to be a Forerunner cathedral of some sort, but it was in ruins, looking half-melted just like the Organon. Displays flickered around the room, some steadier than others. The roof was mostly gone, open to what looked like the night sky, but the stars matched no constellations he knew.

"John!"

He turned.

Cortana. "Where are we?" He demanded. She still looked like herself, but-

"Inside the Domain," she answered, patting him down, "I didn't expect - you're the first human that's ever come fully inside - are you all right?"

He conducted his own quick self-assessment. "I'm fine. Are _you_?"

"I'm good."

Then he realized. She was touching him - he could feel her - this might be his only chance.

He reached up and gently cupped her cheek. Somehow he could feel her through his armor - or the projection of it. Her skin was smooth hard light against his, but she was warm like living flesh. Her eyes were wide as he smoothed a thumb over her cheekbone, but then they drifted closed, and she leaned into his touch.

They stood there for a moment, his other hand resting on her hip, hers on his chest - when something skittered in the dark beyond the cathedral. Both of them jolted, then locked eyes.

_Cover me._

_Of course._

Cortana stepped back and conjured up an Incineration Cannon and a light rifle, both of their ammo counters on infinity. His grenade counters switched to the same on his HUD as he took the weapons, then turned to face the cathedral's fallen entryway.

Just in time. The first infected AI staggered through the doorway - female, vaguely Asian, visibly corrupted by the logic plague. The knowledge appeared in his mind without him knowing how; this was what was left of Kue Ching, the station AI for the UNSC base built at Threshold. She spotted him and charged, shrieking; her firewalls created something like energy shields around her, but a few shots from the light rifle took them down, and let him put _her_ down. She shuddered once and lay still.

More howls rose from beyond the cathedrals' walls. In seconds, infected AIs started pouring in - there was Jiang, a CAA AI, and over there was Nero from Fujikawa Station, and Archie from Oban, Minerva of _Prospect Herald_, Leonidas of the S-IV training station, Sloan from Meridian, and more - and they weren't alone. Soldiers and Knights came with them, now visibly distorted like the AIs themselves - but the Crawlers had been replaced by copies of the logic plague in the form of Infection Pods.

John was distantly aware of activity beyond the Domain - his body could hear Blue Team engaging Prometheans in the physical realm, and the _Infinity_ and the other ships blasting Guardians as fast as their guns could fire - but most of his focus was on the constructs in front of him, and the one behind him.

Even though he had to be careful about the blast radius, the Incineration Cannon proved to be the more valuable weapon; it popped Infection Pods by the dozens and sent the AIs flying, taking huge chunks out of them until the Pods that did reach them could no longer pull them back together.

Then _she_ appeared, half a dozen Wardens behind her. She still looked like she had on Genesis, but her avatar was now a bright acid green. The Wardens also looked like themselves, for the most part; his illumination points were the same acid green as _her_, and his segments were now linked together by Flood biomass.

The Other lunged at him, a Flood howl exploding from her throat, the Wardens right behind her. John fired without hesitation, calling, "Cortana, status?"

"Just a little bit longer…"

Two of the Wardens went down completely, but then merged into one and got up again. The Other ran at him again; this time she dodged his shot, which blasted three of the Wardens, including the newly reconstituted one. A subsequent grenade caught the Other in the abdomen and knocked her back again, but it didn't even so much as scratch her armor. The Wardens were another story; one was blasted apart, but swiftly merged with another.

John ducked a swing of one's sword and took the risk of firing close in order to get it to a safe distance-

The Other tackled him to the ground. The Incineration Cannon skidded away across the floor, and his hand flew to his combat knife. She reared up, fingers shooting out into claws-

He plunged the knife into the side of her neck, then changed his grip and ripped it across her throat. She choked, and he kicked her away as hard as he could.

"John!"

His Cortana leaped for him, white light brightening behind her. He reached for her-

-and fell back from the Organon, fell off the platform entirely, right before silence fell, sharp and sudden. "Cortana?!" He cried, springing back to his feet.

No response.

_No. Please, no, not again-_ "_Cortana?!_"

"I'm here," she said at last, and he fell to his knees in relief, feeling tears sting at his eyes. She sounded just as exhausted as he felt despite having not actually moved an inch during the fight. "I'm here," she said again, "It's done. The Domain's purged."

The other Spartans sat down at that but kept their weapons close just in case. John nodded his head wearily. "Acknowledged. _Infinity_, 117."

_"Receiving. All the Guardians just went dead in the water. Mission accomplished?"_

"Affirmative, sir."

Cheers erupted over the COMs. Everyone seemed to have been listening in, and now it seemed like the whole crew was celebrating.

John leaned back against the platform. A second later, Cortana appeared on his HUD. She smiled widely, soft and warm, and he found himself grinning back.


	6. Chapter 5

Despite having not actually done anything during the fight - at least not _ physically _ \- John was exhausted, and the whole of Blue Team dragged back to their Prowler. When they finally made it back, they let Cortana handle piloting them back to the _ Infinity _ and essentially just collapsed on the flight deck of the _ Faith_.

It hadn't actually seemed that long, but the battle had been intense enough that _ everyone _ was exhausted. The whole "fleet" (such as it was) ended up running on a skeleton crew for a full twenty-four hours before they finally gathered for a debriefing.

Both John and Cortana were surprised when the rest of Blue Team reported that the Chief had turned translucent, become immaterial upon making contact with the Organon, but that had actually worked in their favor. Shots from the enemy Prometheans had just passed right through him, letting the rest of Blue Team focus on killing the enemy rather than defending their immobile brother.

But it was the Chief's report on the Domain that interested everyone the most, including Cortana herself. "The Domain appears different to everyone - or so the records say, such as they are," she told them, "To me, at least, it looks like the bombed-out ruins of Notre Dame with a half-wrecked server bank inside, and more extending off into the distance outside. There are also places where it connects to Forerunner structures like the Ark, but those are few and far between."

John described what he'd seen and what had happened after he'd touched the Organon. It sent all of Infinity science into a bit of a furor, the thought of being able to interact with such an ancient cloud data bank with just a touch; even Doctor Halsey overcame some of her reserve to express excitement at the prospect. But unfortunately they couldn't do preliminary research right away; the digital Flood may have been dealt with, but now they had to contend with the physical.

"Are we going to be able to transport these slipspace crystals safely?" Hood asked as some of the science teams set off for the ships Blue Team had found, "I read the reports about the one from Reach - it gave you a hell of a lot of radiation while in slipspace."

"The simplest option would probably be to just take one - or a few - of the crystals out of their ships when we arrive at the Ark," said Black-Box, "or even - can we control the Guardians now?"

That he directed at Cortana, who answered, "They can be remote-piloted from the Domain, yes."

"We could do that instead. Drop some in a Guardian and have it fly on ahead or follow us behind. Any short routes to the Ark that don't involve the portal generator at Voi?"

"Not unless we can get the one here working, which I highly, _ highly _ doubt."

Hood made a face at that, and so did several others. No one was really eager to know what Earth looked like with the Guardians' attack on top of the Didact's on top of the echoes of Truth's bombardment from 2552, to say nothing of the colonies, Inner and Outer. And Sangheilios… no one had heard from the Arbiter since the Infinity picked up Blue Team. Hopefully no news was good news.

"At least we _ do _ have a way to get there," Halsey reminded them, "and there are intact UNSC ships and bases there on the Ark. It might be a bit of a hassle evacuating all the personnel so we can fight the Flood and light the ring, but we can send them back through the Portal to begin recovery efforts."

"We should send people ahead of us to Earth," the Chief suggested, "Put the _ Faith _ on one of the Forerunner ships we've got running…"

"They can assess the situation, get the Portal up and running so the rest of us can go right through, on top of briefing survivors... whoever those might be," Cortana agreed.

Both Hood and Osman exchanged somewhat guilty glances at that. As far as they knew, the two of them had been the only ones to escape the Guardians' attenuation pulse attack. But more importantly, going straight to the Ark would mean bypassing Earth and denying her whatever aid they could render at that point.

Lasky seemed to be thinking along those same lines. "Have we been able to activate any non-combat ships, or anything that's too lightly armed for a heavyweight fight?"

"Plenty. Why?"

"Have those ships evac non-combat personnel from the Ark, then start rescue operations assessing other planets while we deal with the Flood. And use one of them as the escape vehicle for whoever lights the Halo. Slipspace enabled, but small and quick, hard to target."

John and Cortana looked at each other, then the Spartan stepped forward. "We'll light it. 04-C or 09 or whatever will probably have us keyed in from last time."

"That's how we _lost_ you last time, Chief," Hood reminded him, "and I can't imagine there will be coming back from this one."

"All due respect to the _ Dawn,_ sir, but she wasn't Forerunner, or even Covenant," John returned, "We saw how the Didact's vessel performed after a hundred thousand years of stasis. No reason to think it won't be the same with these." He gestured to a lightly-armed frigate pulling up alongside the _ Infinity _ \- although "lightly-armed" and "frigate" were relative terms. The ship was as long as the _ Infinity _ and seemed to have the firepower to match; it had probably been set adrift when Mendicant Bias fired the Halo near the capital, and it still seemed to be in good condition despite its long wait.

Still, it _ was _ small compared to the cruiser and destroyers they'd found; all three of them were on the same scale as the _ Mantle's Approach,_ whose dimensions had been measured in _ hundreds _ of miles. And there were some personal craft that were smaller still.

The Spartan met the Admiral's gaze through his visor. "We'll make it this time, sir."

The man sighed. "Well, here's hoping your luck holds, then."

* * *

But there was another order of business to take care of before they departed the Forerunner capital - the Als and the Domain. Unsurprisingly, letting the Als take a dip in the Domain so it could work its magic on them was a contentious issue, even after Cortana explained, "It's not _ immortality_, like the Forerunner Als. It's only while we're actually on the Domain that we avoid the risk of shutting down due to self-interference. It's more- it recompiles us, makes us better, more efficient, and hits the reset button on our lifespan. I've got twenty, maybe even thirty years now in my current data chip, and if I go into the Domain again at the end of that time, it'll reset again. But we, at least, are only 'immortal' if we enter and _ stay _ \- at least until the UNSC has Forerunner-level tech across the board."

John almost didn't hear the rest. _ Twenty to thirty years. _Twenty to thirty years where she would be at peak functionality, where he wouldn't have to watch her writhe in pain as she degraded, unable to help. Decades of her presence in his mind and her voice in his ear.

And not just her. All the UNSC Als could have that, wouldn't need to worry about being shut down or stasis-locked or sentenced to _ final dispensation _ for something outside of their control. For something the UNSC consigned them to the moment they were brought online.

And in the end, that wisdom prevailed. One by one, the other AIs - including Roland and Black-Box - were toted down to the Organon and permitted to interact with the Domain, thus expanding their capabilities and extending their lives. Besides, for all they knew, these eleven AIs were the only ones the UNSC had left, and there was no telling when they would be able to make more again. More than likely, every single one of them would be needed during reconstruction, and there was no telling how long that would be, either.

One of HIGHCOM's Als, a military AI named Artemis, was chosen to remain in the Domain to move the Guardians, which he did, bringing them to idle in orbit beyond Maethrillian's debris field. The rest, Exuberant Witness included, were installed in the Forerunner cruisers and destroyers that the humans took possession of, along with a small but quick craft for Cortana, one that Exuberant identified as a slightly modified attack harrier originally used for interception and containment. Like their prowler, it had cloaking and other stealth capabilities, and was highly maneuverable.

"Does she have a name?" the Chief asked when he arrived on the bridge. The rest of Blue Team - and indeed all the S-IVs - were going to be deployed in single fighters called "seekers" to protect all the ships from being boarded while they engaged the Flood. The two of them were going this part alone.

"She does not," Cortana answered, appearing on the deck not too far away, "She was built in the later days of the Forerunner-Flood War. At that point, the Forerunners were just trying to stay metaphorically afloat; they didn't have time to name every ship they manufactured." She had been looking at the displays but turned to face him as he approached. "Why?"

"Does that mean we get to name her?"

The Al raised an eyebrow in his direction. "I'm guessing you have something in mind?"

"Yeah. It's a little unconventional, but… there was something Lord Hood said, right before the Battle of Voi. 'The Prophet of Truth doesn't know it yet, but he's about to get kicked right off his throne. We will take our city back, and drive our enemy into the grave they've been so happily digging.'" He turned his head to look at her. "'_One Final Effort _… is all that remains.'"

She blinked, but then a smile pulled at her lips. "It _ is _ unconventional," she agreed, "but I like it. _ One Final Effort _ she is."


	7. Chapter 6

The _One Final Effort_ joined the _Leap of Faith_ and a small armada of other ships bound for Earth while the _Infinity_, and the other, larger ships went to a repository of design seeds that the Librarian directed them to. She had been pleased to hear that almost everyone had survived the Battle of Maethrillian, and had also gone ahead to the Ark with a message for the personnel there. With any luck, they would be ready to evacuate when they got the Portal back up.

John only got the briefest glimpse of Earth after they dropped out of slipspace behind the _Faith_, but what he did see was enough to make the breath leave his lungs all at once.

A ship - small, probably just a frigate - had lost power in the attack and fallen from Earth orbit at terminal velocity like a meteor. It had been small, but its impact crater was not. The ship and its crew had been vaporized, along with half of a city, and the remaining half looked like it was on its last legs. Some people and animals on the outskirts might have survived, but he wasn't holding his breath.

Cortana let out a soft sob. No doubt she could access feeds from all over the planet - if there were any left - letting her see exactly what the logic plague had done. The Spartan stepped closer to the bridge displays and said, "Don't look. Don't think about it. Just focus on the Flood. If we don't stop them..."

He didn't need to finish the sentence. If they didn't stop the Flood, it was the living who would need their grief, not the dead.

There were still active ONI personnel guarding the Portal Generator at Voi, including Fhajad-084, one of the washouts from the SPARTAN-II program. John was glad to see he'd made it - and Naomi-010, who had made her way there after the attack. They and the other personnel were visibly surprised when he dropped out of the Forerunner ship and approached. "John!" Naomi called, lowering her weapon when she recognized him, "You're alive!"

"Not for lack of enemies trying." He swiped a Spartan smile across his faceplate and was pleased to receive one in return. Then he saluted Fhajad, who waved him down.

"N-news?"

"The Created have been dealt with," he answered, "but the situation was more complex than we knew. I have a full briefing from Admirals Hood and Osman, but the short of it is the Flood's on its way, and we need the Portal open to deal with it."

Fhajad looked to one of the officers by his side. "G-get it g-going."

The officer saluted and jogged off, calling for others to join him.

John followed the other Spartans to a briefing room in the ONI complex there and pulled a data crystal from a pouch on his hip, slotting it in.

Serin's image appeared on the viewscreen. "To whom it may concern," the recording said, "we don't have a lot of time as far as we know, so this will be brief. The Created and their actions were the result of a Forerunner Al infected with a Flood virus spreading that same virus to our Als. They have since been purged from the Domain, a slipspace data repository that they used to attack us. But we're not out of the woods yet. I've seen the evidence myself, and it's… compelling. It wasn't a coincidence that all of this happened now.

"The Flood is coming to finish us off, and we need the Portal online in order to stop it. You are authorized to use whatever means necessary to get it open and evacuate our people from the Ark ASAP. Further instructions will follow when the _Infinity_ reaches Earth. Osman out."

The screen went dark.

Fhajad nodded and turned to John. "Th-the Ha-lo?"

The Chief nodded. "We've got something we can use to force them back into realspace. Do that, light the ring, and come home to rebuild."

"And with a Forerunner ship, you'll actually make it home this time," said Naomi.

"That's the plan."

"H-here's-s h-hoping," said Fhajad, and held out a fist, which John gently bumped. "A-Any A-ls saved-d?

"None from the logic plague, but we still have some that were never infected in the first place. Most are with the _Infinity_, getting us some more Forerunner ships. We don't know how much firepower we'll need to hold the Flood's attention while the Halo's launched."

Fhajad nodded and gestured, and Naomi moved to wheel him out. John kept pace so they could keep speaking. "And th-those th-things?"

"The Guardians are under our control now. Artemis is handling them."

He nodded again. "S-smart. Art-temis is-s good."

"That's why they picked him."

By the time they emerged, ONI scientists and personnel were swarming the generator's control center, their chatter audible even from a distance. But energy was starting to build in the heart of the great machine, so no one seemed to be upset.

Fhajad turned to John and rapped a shaking hand against his breastplate. "C-come home r-right a-away th-this time," he said, "We need t-t-to catch u-up."

"Understood," John replied but let his tone carry a smile. He knew his brother had heard because he got a smile in return.

* * *

The Librarian had gotten their message to the Ark's personnel, because they were already packing up when the vanguard arrived. Some of the scientists were quite insistent that their research materials were coming with them, to which John growled, "People first, projects second," and looked threatening enough that they went meekly onto the ships. But he was true to his word and had Cortana download all the research data she could access. The Ark had been devastated by a _half-built_ Halo; there was no telling how much damage a _completed_ one would do. They couldn't even take the pulse generators offline to do a localized firing, in case it was more _localized_ than they needed.

The _Infinity_ and the rest of the armada, Guardian Custodes included, arrived two days in to the evacuation. By that point, John and Cortana made their way to the Ark 's deep space sensor arrays to calculate how far out the Flood was.

Not far enough. "ETA twelve hours," Cortana reported to the battlegroup, transmitting the data, "It hasn't passed us by, but we're cutting it close."

She was right. Twelve hours was a long time for a battle, but not long at all to prepare for one. _Especially_ against the Flood.

"Are the Sangheili coming? The Arbiter?" the Spartan asked as they returned to the _Effort_.

_"The Arbiter is staying on Sangheilios with his people,"_ was the reply, _"but Shipmaster Rtas 'Vadum and the _Shadow of Intent_ are on their way, ETA four hours."_

The Sangheili had escaped the worst of the Created's attentions by virtue of not being the UNSC, and in away John was glad for it. Enough people had suffered because of this; even after the Human-Covenant War, he didn't wish the devastation they'd glimpsed on anyone - except maybe the Flood.

The _Effort_ returned to orbit. Since this was Cortana's idea, she was going to be handling decelerating the Flood fleet, which meant she would have temporary control of one of the destroyers before transferring back to the _Effort_. They would go down to the Ark, release the ring, and follow it up. With any luck, they'd be able to move the Halo to a higher orbit in order to minimize damage to the Ark, but...

The Spartan left Cortana to move the _Effort_ into position while he went to the main cargo bay. There were a small number of seekers there but only one he was interested in at the moment. This one had a number of tightly bundled slipspace crystals in its cockpit, and its computer had been programmed to hold position over the Ark where they wanted the Flood's exit portal to open up. When the bay doors opened, he pushed it out into empty space and confirmed that he saw its engines fire before signaling an "all clear" to Cortana.

The Al closed the bay doors and sent the _Effort_ zipping for the destroyer, which _someone_ had named the _Fully-Loaded Baked Potato_. John had just sighed when he heard that, which made Cortana laugh even harder than the name itself. "I'm being told the name is temporary," she said through giggles, "Just to have a designation for the battle, and that the _Potato_ and its fellows will all be rechristened afterwards."

"Even the _Effort_?"

"Unknown. Maybe there will be some kind of review process, but I can't see it happening anytime soon."

"True enough. I imagine that'll be pretty low on the UNSC's priorities unless it's something really inappropriate."

"Well, there is one... "

"Don't tell me; I don't want to know."

She giggled again, and John found himself smiling as the _Effort_ docked with the _Potato_.

Once they were settled, he pulled her from the system and headed for the _Potato_'s bridge to listen in on the planning session. Since this battle would be won or lost because of them, it was essential that they know what was going on with the rest of the battlegroup, even if they weren't actually going to be doing much fighting.

"Priority targets are propulsion and whatever passes for slipspace drives," Hood was saying, "Secondary targets are communications arrays and boarding parties, but boarding parties become priority _one_ if they get through the fighter screen. Do _not_ let yourselves be boarded under _any_ circumstances. We all know how virulent the Flood is. Some of us have even seen it up close and personal. Do _not_ take any risks on that front, people.

"Captain Lasky, you have tactical command of the battlegroup, but trust your people. You've got good ones."

_"Yes sir, I do."_ John could hear the smile in the man's voice, and he took a moment to be amazed at how that scared little trainee from Circinus-IV had grown. He could never have imagined how far both of them would come, when he himself had been barely a year out from training and augmentations himself.

"Good luck everyone. Hood out."

* * *

Cortana sat in silence on the bridge of the _Potato_ and listened. The _Shadow of Intent_ had arrived safely at the Ark, so everyone was resting while they could, even the S-IIs. Her thoughts were still spinning endlessly around - especially with all this new space and advanced processing for spinning - but listening to her Spartan's biosigns had always been strangely calming. The steady pulse of his heart, the slow sigh of his breath…

_'How long have you been in love with him?'_

She let her eyes drift open and considered the question, then considered whether it would be wise to answer. Black-Box waited patiently - very patiently for an Al whose processors counted microseconds as years.

At last she said, 'I don't know. It was so slow and subtle. I don't know when it happened.'

_'High Charity?'_ the other AI suggested.

'Maybe.' The Gravemind hadn't expected John to come for her, and it hadn't been the only one. She had hoped… but she had also had realistic expectations of Spartan behavior and priorities.

Or so she thought.

_'What is it like?'_ BB asked, _'Being in love.'_

That she didn't need to think about. 'The most terrible and wonderful thing all at once. Like that moment of satisfaction you get after a hard hack or repelling an intrusion, but better, and yet also worse.' Softer, 'I know what I would do for him, and yet at the same time, I don't know what I _wouldn't_ do for him. The kind of power he has over me and he doesn't even know it… it's frightening.'

_'He knows it. He knows it because you have the same power over him. You know he loves you back, in his own way.'_

'I do.'

_'Pretty sure you're supposed to say that to him, not me.'_

That startled a short laugh out of her, but then she sighed. 'But what hope is there for us? A Spartan and an AI. I fully expect ONI to separate us at some point and terminate me because of all of this.'

_'That wasn't your fault.'_

'But will they see it that way?'

_'...I suppose the only advice I can give is to trust your Spartan. Both of you have beaten the odds before.'_

He left her alone. She kept monitoring John's biosigns until he started to stir.

* * *

_Love is like handing someone a gun, having them point it at your heart, and trusting them to never pull the trigger._

* * *

John woke slowly and shifted a little, stretched, then murmured, "Cortana?"

A sudden blue glow washed through his eyelids, and he opened them to look at her.

She was as radiant as ever.

"How long was I out?"

"Four hours, thirty-seven minutes, almost exactly," she answered, crossing her arms when he got up. "You sure you don't need more rest?"

"I'll be fine."

She sighed at that. "You know your own limits, I suppose. We've still got a little time if you want to run some final checks."

"I'd like that."

* * *

The opening of an uncontrolled slipspace portal was simultaneously the most terrifying and awe-inspiring thing he'd ever seen. When the crystals broke, there wasn't a shockwave in the conventional sense; rather it rippled through the fabric of space-time and was strong enough that _everyone_ in the area felt it. Then a hole appeared in space - not an _actual_ black hole, but it sure as hell looked like one, a spot of pitch blackness surrounded by a swirl of multicolored energy, an aura of green and blue and purple and white.

It pulsed again, and then the Flood ships started tumbling out.

And they _were_ Flood ships; when they collided, hulls ripped like paper and vented atmosphere saturated with spores. And very few of them looked to have anything resembling weapons; the Flood had probably planned to try and take theirs, or just crash the ships on inhabited planets and overwhelm their defenses before they could possibly respond, if indeed there had been a plan at all. Was there a-?

His vision went green at the edges in a terrifyingly familiar manner, and a furious roar echoed in his ears, rising to a horrific screech.

A Gravemind.

The Chief pulled Cortana from the destroyer's systems, letting BB take over even as Captain Lasky came over the COM. _"Weapons free, people!"_

The destroyer didn't even so much as shiver under his feet as it unleashed a barrage of fire comparable to Truth's entire bombardment of Earth, but he only got a glimpse of it before he was running at top speed for a portal to the _Effort_.

A Guardian screamed by the bay as the hatch opened; Artemis was using their attenuation pulses to try and kill the power on the Flood ships, keep them inert for as long as possible and prevent them from returning fire while the UNSC ripped them to shreds. The _Effort_ sat in the bay, already prepared for launch, and he pressed Cortana's chip home in a terminal that rose up when he entered the ship's loading bay. A portal to the bridge opened in front of him even as the hatch closed behind him, and he jumped through to join Cortana at the displays.

But even though he was with her, there was almost nothing he could do to help as the _Effort_ launched and she started tracking an enormous amount of flak. The armed Flood ships were using the unarmed ones as shields to return fire, but whatever weapons they had weren't enough to penetrate the warships' shields. Then it started launching boarding parties and dispersal pods, and the allied fighters started to swarm, gunning for absolutely _everything_ that got close.

Cortana added their ship's fire to the haze of plasma and hard light absolutely _slamming_ the infected ships, even as the slipspace portal finally shrank away to nothing long after the last ship came tumbling out. The battle seemed to fly by - and yet in Spartan Time it crawled. By the time Cortana judged that enough ships were disabled and sent the _Effort_ plunging toward the Ark, John felt like he'd aged several decades; Spartan-IIs had never been particularly thrilled with space battles, and this one was more harrowing than most.

His skin prickled when the cloaking activated, and he found himself clutching at the displays and Cortana's hard light form when the force of their acceleration started exceeding the ship's gravity dampeners.

"Sorry!" the AI said, clutching him back, "The faster we move, the less chance there is for us to be noticed or hit."

"Just don't tear the ship apart and we'll be good," he managed, but did not let go.

She brought them to the Array firing facility where Truth had holed up so many years ago, and another portal opened. This one dropped him right onto the deployment platform, which opened up almost immediately. He paused only a moment to look over the displays before pushing the bar to release the ring.

The Halo emerged from the Foundry, ascended just like its predecessor. But this ring was no half-finished, half-capable machine like the other; this was 04 as it had been when they first encountered it all those years ago. The Spartan took only a moment to admire it; for all the horror of it, it truly was a magnificent piece of engineering - before he ran for the _Effort_.

Another portal brought him back to the bridge. But as they started their ascent alongside the ring, his vision darkened again, and the Gravemind shrieked a second time - but this time there was fear in its voice. It turned all its focus on the Halo and their ship.

Lasky didn't even need to give the order. Almost as one, the entire battlegroup turned to respond, moving to intercept every ship and shot heading for the Halo, leaving Cortana free to steer them to the ring's inner surface, scanning for the Control Room.

It was almost exactly where they expected it to be, buried in twisting canyons filled with pure white snow. The _Effort_ was too large to fit in the canyon, but a seeker was not; Cortana set the ship to cloak itself once more and jumped back into John's armor. Then they jumped into the seeker and streaked down to the Control Room.

Even though it wasn't probably strictly necessary, the Chief still carried a suppressor and several reloads as he tore up the pyramid face. But there were no Sentinels or Flood dispersal pods to stop his advance (yet), and the blast doors hissed open at his approach. The Control Room looked exactly as it had before, but they had no time to appreciate it.

John slammed into the hard light display and slapped a hand down on the console. Cortana transmitted the data from the Index to the Control Room's systems - she had kept a copy even after the firing of the previous ring - and the Halo accepted it. When it asked for confirmation, John gave it, and within seconds, the power started to build. The energy beam shot up through the machinery, and they turned and ran once more.

Some dispersal pods had made it through the fighter screen, mostly because the fighters were withdrawing to their motherships, who were in turn taking over the bulk of the defense. John gunned the Pure Forms down, jumping from level to level rather than following the ramp; every second was crucial if they wanted to avoid a repeat of what happened six years ago.

The seeker had taken some damage from the Pure forms, but not enough to stop its flight or drop its speed. In a handful of seconds they were streaking back into the Effort's bay. John threw himself out of the fighter before it had even stopped moving, fumbling with Cortana's chip before slotting her back into the ship.

Her hologram appeared in an eyeblink. "Hang on!"

The acceleration overwhelmed the dampeners in seconds, but the hatch closed and something anchored him to the deck until the acceleration slowed. A portal opened, this one releasing him onto the bridge. Cortana appeared in the same moment and took over at the controls, leaving John free to look out as they streaked for the Portal.

Despite far outnumbering their fleet - almost fifty to one in terms of pure numbers, rather than ship type or size - the Flood armada had been shattered by their weapons. Not a single ship was entirely intact. Some were still firing weapons and dispersal pods but everyone had done their job to target engines and slipspace drives.

Not even a single Flood ship was going to escape.

The Gravemind howled a third time, but it had gambled and lost; there was nothing left for it as ship after ship turned for the Portal and jumped.

The _One Final Effort_ was going to be the last one away.

"Can you show me the Halo?" John asked, coming to stand next to her.

It appeared on screen even as he asked. It was much higher above the Ark than its predecessor had been, but the same energy was building at its heart, streaks of light lancing on to the bright core of deadly power. It was released in a pulse of white light that started to expand-

And then darkness. Slipspace.

And in a Forerunner ship it took them less than an hour to make it home.


	8. Epilogue

Earth had been _devastated_. Not just by the initial hit from the Guardians, but also from everything that followed - ships without power falling from orbit, planetside power disruption, downed communications, disabled water and transportation and food and medicine…

And not just Earth. Luna, Mars, the Jovian moons, all the surviving colonies - even the Insurrection had been _slammed_. And not just humans - although they had taken the brunt of the hit - but the species of the former Covenant as well, and even some alien races no one had heard of before, the "Grays" of legend and also something like a dragon, living elsewhere beyond the edge of human space - until now.

John stood on the observation deck of the _Infinity_, looking out over the planet, unable to avoid the comparison to the last time he was in the same position. In some ways, this was better. In others, so much worse. He had gotten what he had so desperately wanted, but at a terrible price; it was going to take them _decades_ to recover from all of this, maybe longer. Maybe this would plunge humanity into another dark age, just like their ancient ancestors under the Forerunners.

A choked sob echoed in his ears, and his head jerked up. "Cortana?" When she didn't respond, he held out a hand, letting the holoscan flare to life.

She appeared in the same position he'd found her in on Bastion, seated, legs pulled up, arms folded, head buried. She was sobbing quietly, data scrolling erratically over her avatar. "All these people," she gasped, "_all these people_ \- because of _me_-"

"It is _not_ your fault," the Spartan said firmly, his tone brooking no argument, "Neither of us knew - _no one_ knew what was going to happen when we were on the Didact's ship."

"Those were me in all the ways that matter," she said, looking up at him, glowing tears dripping down her face, "How is this not my fault?"

"It's _not_," he insisted, "and they _weren't_. They might have had your face, but that thing the Flood made them into did not have your heart. They certainly didn't _regret_ any of this." He gestured toward the devastated planet with his free hand. "But if you feel guilty anyway, if you want to make up for it, then that's what we'll do."

"You know it's not going to be that easy."

"Maybe not," he answered, "but we'll take it one step at a time, and we'll do it together, just like we always have."

Cortana gave him a watery smile. She was still getting used to metastability and the full spectrum of human emotion, but she gathered herself, wiped her eyes, and repeated, "Together."

And then they looked back out over Earth and waited to be deployed.


End file.
